1. Field of the Invention
The invention is in the field of textile technology and relates to an apparatus, which is used for the continuous crimping of threads made from thermoplastic material.
2. Discussion of the Background of the Invention and Material Information
Apparatuses for the continuous crimping of threads made from thermoplastic material are e.g. described in European patent publication 310890, also assigned to the assignee of the present invention. The apparatuses described herein have a stationary crimping nozzle with a feed channel, as well as a nozzle orifice and a rotary plug feed roller. The crimping nozzle is positioned substantially tangentially to the plug feed roller in such a way that the nozzle orifice, and a guide fork fitted in the vicinity of said orifice, projects between two parallel, interrupted, lateral guide means passing around the circumference of the plug feed roller. The stuffer box is on the one hand bounded by the stationary parts of the guide fork and on the other by the lateral guide means rotating with the plug feed roller.
For crimping purposes the thread is conveyed, by means of a heated feed medium, under pressure through the feed channel and against the nozzle orifice and is simultaneously heated. Immediately outside the nozzle orifice the feed medium expands and the thread is accumulated in the stuffer box to form a plug, which is then guided by the lateral guide means and conveyed away on the plug feed roller. The thread speed in the feed channel is higher than the circumferential speed of the plug feed roller (plug speed). In order that the feed medium can expand in the vicinity of the nozzle orifice, the lateral guide means are shaped in an interrupted form. Rows of radially positioned needles have proven themselves to be particularly advantageous as lateral guide means.
In most applications, since a plurality of parallel. moving threads are produced, the plug feed roller has several pairs of lateral guide means for each plug which are parallel and spaced with respect to one another.
It has been determined that, in particular with rollers for several pairs of needle rows, transverse flows occur during operation (in the axial direction of the plug feed roller), which have a disadvantageous effect on plug formation. It has also been determined that such plug feed rollers, and in particular those with needle rows (needle rollers), are difficult to handle and are easily damaged during replacement, particularly in the heated state.